Troubleshooting
Cornflower problems — and how to fix them
Cornflower (Centaurea cyanus) is generally low-drama, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Powdery mildew
The most common problem, especially on plants sown too densely or in hot, dry weather following overwatering; improve air circulation by thinning, and avoid wetting foliage.
Aphids
Black bean aphid (Aphis fabae) and other species cluster on stem tips and buds in early summer; blast off with water or apply an insecticidal soap spray, as heavy infestations distort and abort flowers.
Prevent cornflower problems before they start
Most cornflower issues are care-mismatch, not bad luck. Dial in the basics:
Cornflower problems — FAQ
Why is my cornflower powdery mildew?
The most common problem, especially on plants sown too densely or in hot, dry weather following overwatering; improve air circulation by thinning, and avoid wetting foliage.
Why is my cornflower aphids?
Black bean aphid (Aphis fabae) and other species cluster on stem tips and buds in early summer; blast off with water or apply an insecticidal soap spray, as heavy infestations distort and abort flowers.